Thirst Current Biology David E. Leib, Christopher A. Zimmerman, Zachary A. Knight  Current Biology  Volume 26, Issue 24, Pages R1260-R1265 (December 2016) DOI: 10.1016/j.cub.2016.11.019 Copyright © 2016 Elsevier Ltd Terms and Conditions

Figure 1 Physiological effects of deviations in plasma osmolality. The normal range of plasma osmolality is 280–295 milliosmoles (mOsm). A one percent increase in osmolality is detected as the sensation of thirst. Irritability and lethargy are observed in the yellow range, and more severe effects become evident at larger deviations. A decrease in osmolality of two percent can suppress thirst induced by hypovolemia. Current Biology 2016 26, R1260-R1265DOI: (10.1016/j.cub.2016.11.019) Copyright © 2016 Elsevier Ltd Terms and Conditions

Figure 2 Intracellular versus extracellular dehydration. Current Biology 2016 26, R1260-R1265DOI: (10.1016/j.cub.2016.11.019) Copyright © 2016 Elsevier Ltd Terms and Conditions

Figure 3 The neural circuit that controls thirst. (A) A set of integrated brain structures called the lamina terminalis monitors the state of the blood and generates appropriate motivational, autonomic, and hormonal responses. The subfornical organ (SFO) and organum vasculosum of the lamina terminalis (OVLT) directly sense circulating factors and, along with the median preoptic nucleus (MnPO), integrate this information and communicate with downstream brain regions. AC, anterior commissure; F, fornix; 3V, third ventricle. (B) The downstream circuit that controls the autonomic and hormonal responses to fluid imbalance relies on projections from the lamina terminalis to the paraventricular nucleus of the hypothalamus (PVH) and the supraoptic nucleus (SON). (C) The downstream circuit that generates thirst is less clear, although many brain regions have been implicated in the central representation of thirst and as relay and effector/output nuclei. These brain regions were identified using c-Fos mapping studies in rodents and fMRI/PET mapping studies in humans. ACC, anterior cingulate cortex; AP, area postrema; BNST, bed nucleus of the stria terminalis; CeA, central amygdala; INS, insular cortex; NTS, nucleus tractus solitarii; PAG, periaqueductal gray; PBN, parabrachial nucleus; PVT, paraventricular nucleus of the thalamus; RN, raphe nuclei; VLM, ventrolateral motor nucleus. Current Biology 2016 26, R1260-R1265DOI: (10.1016/j.cub.2016.11.019) Copyright © 2016 Elsevier Ltd Terms and Conditions

Figure 4 Hormonal stimuli for thirst. (A) The most potent hormonal stimulus for thirst is angiotensin II (AngII), which is generated when the rate-limiting enzyme renin is secreted by the kidneys in response to hypovolemia or hypotension. Other hormonal stimuli for thirst are secreted by the stomach and pancreas during eating, as well as by the ovaries during pregnancy. Atrial natriuretic peptide, a potent inhibitor of thirst, is secreted by the heart in response to hypertension. (B) The physiological stimuli that induce secretion of thirst-related hormones include changes in plasma volume and pressure, as well as eating and pregnancy. Decreases in blood volume and pressure increase levels of the dipsogenic hormone angiotensin II, whereas increases in blood volume increase levels of the thirst-inhibiting hormone atrial natriuretic peptide (ANP). Illustration from NIDDK Image Library. Current Biology 2016 26, R1260-R1265DOI: (10.1016/j.cub.2016.11.019) Copyright © 2016 Elsevier Ltd Terms and Conditions